It’s hardly dodgy. He tested and charged each cell to the correct capacity before wiring it up. He 3D printed an interlocking battery holder. He even installed a BMS with a temp sensor.
Dude’s build is significantly better than some of the shit China is trying to sell on Amazon.
You gotta give credit where credit is due.
I haven’t been on a Boeing 737 ever since the MH370 crash. I actively avoid getting on a Boeing and only been on a 787 once since.